which screws for raco 7120 outlet box / for light fixtures

I have a Raco 7120 outlet box in ceiling and #10 10-32 screws don't fit. They are too loose/small for the holes in the outlet box. Do you know which size screws this box uses and if there are cross bars that accept bigger screws? Most cross bars I found at Home Depot seem for 8-32/10-32 max...